FM / io

/usr/src/linux-headers-5.15.0-190/include/xen/interface/io/

/usr/src/linux-headers-5.15.0-190/include/xen/interface/io

Name	Size	Mode	Actions
9pfs.h	1466	0644	edit dl rm
blkif.h	13206	0644	edit dl rm
console.h	587	0644	edit dl rm
displif.h	44263	0644	edit dl rm
fbif.h	4586	0644	edit dl rm
kbdif.h	24273	0644	edit dl rm
netif.h	35590	0644	edit dl rm
pciif.h	3601	0644	edit dl rm
protocols.h	697	0644	edit dl rm
pvcalls.h	3113	0644	edit dl rm
ring.h	23756	0644	edit dl rm
sndif.h	49478	0644	edit dl rm
tpmif.h	1704	0644	edit dl rm
vscsiif.h	8908	0644	edit dl rm
xenbus.h	1173	0644	edit dl rm
xs_wire.h	2263	0644	edit dl rm

Edit: /usr/src/linux-headers-5.15.0-190/include/xen/interface/io/sndif.h (49478B)

/******************************************************************************
 * sndif.h
 *
 * Unified sound-device I/O interface for Xen guest OSes.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Copyright (C) 2013-2015 GlobalLogic Inc.
 * Copyright (C) 2016-2017 EPAM Systems Inc.
 *
 * Authors: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
 *          Oleksandr Grytsov <oleksandr_grytsov@epam.com>
 *          Oleksandr Dmytryshyn <oleksandr.dmytryshyn@globallogic.com>
 *          Iurii Konovalenko <iurii.konovalenko@globallogic.com>
 */

#ifndef __XEN_PUBLIC_IO_SNDIF_H__
#define __XEN_PUBLIC_IO_SNDIF_H__

#include "ring.h"
#include "../grant_table.h"

/*
 ******************************************************************************
 *                           Protocol version
 ******************************************************************************
 */
#define XENSND_PROTOCOL_VERSION	2

/*
 ******************************************************************************
 *                  Feature and Parameter Negotiation
 ******************************************************************************
 *
 * Front->back notifications: when enqueuing a new request, sending a
 * notification can be made conditional on xensnd_req (i.e., the generic
 * hold-off mechanism provided by the ring macros). Backends must set
 * xensnd_req appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
 *
 * Back->front notifications: when enqueuing a new response, sending a
 * notification can be made conditional on xensnd_resp (i.e., the generic
 * hold-off mechanism provided by the ring macros). Frontends must set
 * xensnd_resp appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()).
 *
 * The two halves of a para-virtual sound card driver utilize nodes within
 * XenStore to communicate capabilities and to negotiate operating parameters.
 * This section enumerates these nodes which reside in the respective front and
 * backend portions of XenStore, following the XenBus convention.
 *
 * All data in XenStore is stored as strings. Nodes specifying numeric
 * values are encoded in decimal. Integer value ranges listed below are
 * expressed as fixed sized integer types capable of storing the conversion
 * of a properly formated node string, without loss of information.
 *
 ******************************************************************************
 *                        Example configuration
 ******************************************************************************
 *
 * Note: depending on the use-case backend can expose more sound cards and
 * PCM devices/streams than the underlying HW physically has by employing
 * SW mixers, configuring virtual sound streams, channels etc.
 *
 * This is an example of backend and frontend configuration:
 *
 *--------------------------------- Backend -----------------------------------
 *
 * /local/domain/0/backend/vsnd/1/0/frontend-id = "1"
 * /local/domain/0/backend/vsnd/1/0/frontend = "/local/domain/1/device/vsnd/0"
 * /local/domain/0/backend/vsnd/1/0/state = "4"
 * /local/domain/0/backend/vsnd/1/0/versions = "1,2"
 *
 *--------------------------------- Frontend ----------------------------------
 *
 * /local/domain/1/device/vsnd/0/backend-id = "0"
 * /local/domain/1/device/vsnd/0/backend = "/local/domain/0/backend/vsnd/1/0"
 * /local/domain/1/device/vsnd/0/state = "4"
 * /local/domain/1/device/vsnd/0/version = "1"
 *
 *----------------------------- Card configuration ----------------------------
 *
 * /local/domain/1/device/vsnd/0/short-name = "Card short name"
 * /local/domain/1/device/vsnd/0/long-name = "Card long name"
 * /local/domain/1/device/vsnd/0/sample-rates = "8000,32000,44100,48000,96000"
 * /local/domain/1/device/vsnd/0/sample-formats = "s8,u8,s16_le,s16_be"
 * /local/domain/1/device/vsnd/0/buffer-size = "262144"
 *
 *------------------------------- PCM device 0 --------------------------------
 *
 * /local/domain/1/device/vsnd/0/0/name = "General analog"
 * /local/domain/1/device/vsnd/0/0/channels-max = "5"
 *
 *----------------------------- Stream 0, playback ----------------------------
 *
 * /local/domain/1/device/vsnd/0/0/0/type = "p"
 * /local/domain/1/device/vsnd/0/0/0/sample-formats = "s8,u8"
 * /local/domain/1/device/vsnd/0/0/0/unique-id = "0"
 *
 * /local/domain/1/device/vsnd/0/0/0/ring-ref = "386"
 * /local/domain/1/device/vsnd/0/0/0/event-channel = "15"
 * /local/domain/1/device/vsnd/0/0/0/evt-ring-ref = "1386"
 * /local/domain/1/device/vsnd/0/0/0/evt-event-channel = "215"
 *
 *------------------------------ Stream 1, capture ----------------------------
 *
 * /local/domain/1/device/vsnd/0/0/1/type = "c"
 * /local/domain/1/device/vsnd/0/0/1/channels-max = "2"
 * /local/domain/1/device/vsnd/0/0/1/unique-id = "1"
 *
 * /local/domain/1/device/vsnd/0/0/1/ring-ref = "384"
 * /local/domain/1/device/vsnd/0/0/1/event-channel = "13"
 * /local/domain/1/device/vsnd/0/0/1/evt-ring-ref = "1384"
 * /local/domain/1/device/vsnd/0/0/1/evt-event-channel = "213"
 *
 *------------------------------- PCM device 1 --------------------------------
 *
 * /local/domain/1/device/vsnd/0/1/name = "HDMI-0"
 * /local/domain/1/device/vsnd/0/1/sample-rates = "8000,32000,44100"
 *
 *------------------------------ Stream 0, capture ----------------------------
 *
 * /local/domain/1/device/vsnd/0/1/0/type = "c"
 * /local/domain/1/device/vsnd/0/1/0/unique-id = "2"
 *
 * /local/domain/1/device/vsnd/0/1/0/ring-ref = "387"
 * /local/domain/1/device/vsnd/0/1/0/event-channel = "151"
 * /local/domain/1/device/vsnd/0/1/0/evt-ring-ref = "1387"
 * /local/domain/1/device/vsnd/0/1/0/evt-event-channel = "351"
 *
 *------------------------------- PCM device 2 --------------------------------
 *
 * /local/domain/1/device/vsnd/0/2/name = "SPDIF"
 *
 *----------------------------- Stream 0, playback ----------------------------
 *
 * /local/domain/1/device/vsnd/0/2/0/type = "p"
 * /local/domain/1/device/vsnd/0/2/0/unique-id = "3"
 *
 * /local/domain/1/device/vsnd/0/2/0/ring-ref = "389"
 * /local/domain/1/device/vsnd/0/2/0/event-channel = "152"
 * /local/domain/1/device/vsnd/0/2/0/evt-ring-ref = "1389"
 * /local/domain/1/device/vsnd/0/2/0/evt-event-channel = "452"
 *
 ******************************************************************************
 *                            Backend XenBus Nodes
 ******************************************************************************
 *
 *----------------------------- Protocol version ------------------------------
 *
 * versions
 *      Values:         <string>
 *
 *      List of XENSND_LIST_SEPARATOR separated protocol versions supported
 *      by the backend. For example "1,2,3".
 *
 ******************************************************************************
 *                            Frontend XenBus Nodes
 ******************************************************************************
 *
 *-------------------------------- Addressing ---------------------------------
 *
 * dom-id
 *      Values:         <uint16_t>
 *
 *      Domain identifier.
 *
 * dev-id
 *      Values:         <uint16_t>
 *
 *      Device identifier.
 *
 * pcm-dev-idx
 *      Values:         <uint8_t>
 *
 *      Zero based contigous index of the PCM device.
 *
 * stream-idx
 *      Values:         <uint8_t>
 *
 *      Zero based contigous index of the stream of the PCM device.
 *
 * The following pattern is used for addressing:
 *   /local/domain/<dom-id>/device/vsnd/<dev-id>/<pcm-dev-idx>/<stream-idx>/...
 *
 *----------------------------- Protocol version ------------------------------
 *
 * version
 *      Values:         <string>
 *
 *      Protocol version, chosen among the ones supported by the backend.
 *
 *------------------------------- PCM settings --------------------------------
 *
 * Every virtualized sound frontend has a set of PCM devices and streams, each
 * could be individually configured. Part of the PCM configuration can be
 * defined at higher level of the hierarchy and be fully or partially re-used
 * by the underlying layers. These configuration values are:
 *  o number of channels (min/max)
 *  o supported sample rates
 *  o supported sample formats.
 * E.g. one can define these values for the whole card, device or stream.
 * Every underlying layer in turn can re-define some or all of them to better
 * fit its needs. For example, card may define number of channels to be
 * in [1; 8] range, and some particular stream may be limited to [1; 2] only.
 * The rule is that the underlying layer must be a subset of the upper layer
 * range.
 *
 * channels-min
 *      Values:         <uint8_t>
 *
 *      The minimum amount of channels that is supported, [1; channels-max].
 *      Optional, if not set or omitted a value of 1 is used.
 *
 * channels-max
 *      Values:         <uint8_t>
 *
 *      The maximum amount of channels that is supported.
 *      Must be at least <channels-min>.
 *
 * sample-rates
 *      Values:         <list of uint32_t>
 *
 *      List of supported sample rates separated by XENSND_LIST_SEPARATOR.
 *      Sample rates are expressed as a list of decimal values w/o any
 *      ordering requirement.
 *
 * sample-formats
 *      Values:         <list of XENSND_PCM_FORMAT_XXX_STR>
 *
 *      List of supported sample formats separated by XENSND_LIST_SEPARATOR.
 *      Items must not exceed XENSND_SAMPLE_FORMAT_MAX_LEN length.
 *
 * buffer-size
 *      Values:         <uint32_t>
 *
 *      The maximum size in octets of the buffer to allocate per stream.
 *
 *----------------------- Virtual sound card settings -------------------------
 * short-name
 *      Values:         <char[32]>
 *
 *      Short name of the virtual sound card. Optional.
 *
 * long-name
 *      Values:         <char[80]>
 *
 *      Long name of the virtual sound card. Optional.
 *
 *----------------------------- Device settings -------------------------------
 * name
 *      Values:         <char[80]>
 *
 *      Name of the sound device within the virtual sound card. Optional.
 *
 *----------------------------- Stream settings -------------------------------
 *
 * type
 *      Values:         "p", "c"
 *
 *      Stream type: "p" - playback stream, "c" - capture stream
 *
 *      If both capture and playback are needed then two streams need to be
 *      defined under the same device.
 *
 * unique-id
 *      Values:         <string>
 *
 *      After stream initialization it is assigned a unique ID, so every
 *      stream of the frontend can be identified by the backend by this ID.
 *      This can be UUID or such.
 *
 *-------------------- Stream Request Transport Parameters --------------------
 *
 * event-channel
 *      Values:         <uint32_t>
 *
 *      The identifier of the Xen event channel used to signal activity
 *      in the ring buffer.
 *
 * ring-ref
 *      Values:         <uint32_t>
 *
 *      The Xen grant reference granting permission for the backend to map
 *      a sole page in a single page sized ring buffer.
 *
 *--------------------- Stream Event Transport Parameters ---------------------
 *
 * This communication path is used to deliver asynchronous events from backend
 * to frontend, set up per stream.
 *
 * evt-event-channel
 *      Values:         <uint32_t>
 *
 *      The identifier of the Xen event channel used to signal activity
 *      in the ring buffer.
 *
 * evt-ring-ref
 *      Values:         <uint32_t>
 *
 *      The Xen grant reference granting permission for the backend to map
 *      a sole page in a single page sized ring buffer.
 *
 ******************************************************************************
 *                               STATE DIAGRAMS
 ******************************************************************************
 *
 * Tool stack creates front and back state nodes with initial state
 * XenbusStateInitialising.
 * Tool stack creates and sets up frontend sound configuration nodes per domain.
 *
 * Front                                Back
 * =================================    =====================================
 * XenbusStateInitialising              XenbusStateInitialising
 *                                       o Query backend device identification
 *                                         data.
 *                                       o Open and validate backend device.
 *                                                      |
 *                                                      |
 *                                                      V
 *                                      XenbusStateInitWait
 *
 * o Query frontend configuration
 * o Allocate and initialize
 *   event channels per configured
 *   playback/capture stream.
 * o Publish transport parameters
 *   that will be in effect during
 *   this connection.
 *              |
 *              |
 *              V
 * XenbusStateInitialised
 *
 *                                       o Query frontend transport parameters.
 *                                       o Connect to the event channels.
 *                                                      |
 *                                                      |
 *                                                      V
 *                                      XenbusStateConnected
 *
 *  o Create and initialize OS
 *    virtual sound device instances
 *    as per configuration.
 *              |
 *              |
 *              V
 * XenbusStateConnected
 *
 *                                      XenbusStateUnknown
 *                                      XenbusStateClosed
 *                                      XenbusStateClosing
 * o Remove virtual sound device
 * o Remove event channels
 *              |
 *              |
 *              V
 * XenbusStateClosed
 *
 *------------------------------- Recovery flow -------------------------------
 *
 * In case of frontend unrecoverable errors backend handles that as
 * if frontend goes into the XenbusStateClosed state.
 *
 * In case of backend unrecoverable errors frontend tries removing
 * the virtualized device. If this is possible at the moment of error,
 * then frontend goes into the XenbusStateInitialising state and is ready for
 * new connection with backend. If the virtualized device is still in use and
 * cannot be removed, then frontend goes into the XenbusStateReconfiguring state
 * until either the virtualized device removed or backend initiates a new
 * connection. On the virtualized device removal frontend goes into the
 * XenbusStateInitialising state.
 *
 * Note on XenbusStateReconfiguring state of the frontend: if backend has
 * unrecoverable errors then frontend cannot send requests to the backend
 * and thus cannot provide functionality of the virtualized device anymore.
 * After backend is back to normal the virtualized device may still hold some
 * state: configuration in use, allocated buffers, client application state etc.
 * So, in most cases, this will require frontend to implement complex recovery
 * reconnect logic. Instead, by going into XenbusStateReconfiguring state,
 * frontend will make sure no new clients of the virtualized device are
 * accepted, allow existing client(s) to exit gracefully by signaling error
 * state etc.
 * Once all the clients are gone frontend can reinitialize the virtualized
 * device and get into XenbusStateInitialising state again signaling the
 * backend that a new connection can be made.
 *
 * There are multiple conditions possible under which frontend will go from
 * XenbusStateReconfiguring into XenbusStateInitialising, some of them are OS
 * specific. For example:
 * 1. The underlying OS framework may provide callbacks to signal that the last
 *    client of the virtualized device has gone and the device can be removed
 * 2. Frontend can schedule a deferred work (timer/tasklet/workqueue)
 *    to periodically check if this is the right time to re-try removal of
 *    the virtualized device.
 * 3. By any other means.
 *
 ******************************************************************************
 *                             PCM FORMATS
 ******************************************************************************
 *
 * XENSND_PCM_FORMAT_<format>[_<endian>]
 *
 * format: <S/U/F><bits> or <name>
 *     S - signed, U - unsigned, F - float
 *     bits - 8, 16, 24, 32
 *     name - MU_LAW, GSM, etc.
 *
 * endian: <LE/BE>, may be absent
 *     LE - Little endian, BE - Big endian
 */
#define XENSND_PCM_FORMAT_S8		0
#define XENSND_PCM_FORMAT_U8		1
#define XENSND_PCM_FORMAT_S16_LE	2
#define XENSND_PCM_FORMAT_S16_BE	3
#define XENSND_PCM_FORMAT_U16_LE	4
#define XENSND_PCM_FORMAT_U16_BE	5
#define XENSND_PCM_FORMAT_S24_LE	6
#define XENSND_PCM_FORMAT_S24_BE	7
#define XENSND_PCM_FORMAT_U24_LE	8
#define XENSND_PCM_FORMAT_U24_BE	9
#define XENSND_PCM_FORMAT_S32_LE	10
#define XENSND_PCM_FORMAT_S32_BE	11
#define XENSND_PCM_FORMAT_U32_LE	12
#define XENSND_PCM_FORMAT_U32_BE	13
#define XENSND_PCM_FORMAT_F32_LE	14 /* 4-byte float, IEEE-754 32-bit, */
#define XENSND_PCM_FORMAT_F32_BE	15 /* range -1.0 to 1.0              */
#define XENSND_PCM_FORMAT_F64_LE	16 /* 8-byte float, IEEE-754 64-bit, */
#define XENSND_PCM_FORMAT_F64_BE	17 /* range -1.0 to 1.0              */
#define XENSND_PCM_FORMAT_IEC958_SUBFRAME_LE 18
#define XENSND_PCM_FORMAT_IEC958_SUBFRAME_BE 19
#define XENSND_PCM_FORMAT_MU_LAW	20
#define XENSND_PCM_FORMAT_A_LAW		21
#define XENSND_PCM_FORMAT_IMA_ADPCM	22
#define XENSND_PCM_FORMAT_MPEG		23
#define XENSND_PCM_FORMAT_GSM		24

/*
 ******************************************************************************
 *                             REQUEST CODES
 ******************************************************************************
 */
#define XENSND_OP_OPEN			0
#define XENSND_OP_CLOSE			1
#define XENSND_OP_READ			2
#define XENSND_OP_WRITE			3
#define XENSND_OP_SET_VOLUME		4
#define XENSND_OP_GET_VOLUME		5
#define XENSND_OP_MUTE			6
#define XENSND_OP_UNMUTE		7
#define XENSND_OP_TRIGGER		8
#define XENSND_OP_HW_PARAM_QUERY	9

#define XENSND_OP_TRIGGER_START		0
#define XENSND_OP_TRIGGER_PAUSE		1
#define XENSND_OP_TRIGGER_STOP		2
#define XENSND_OP_TRIGGER_RESUME	3

/*
 ******************************************************************************
 *                                 EVENT CODES
 ******************************************************************************
 */
#define XENSND_EVT_CUR_POS		0

/*
 ******************************************************************************
 *               XENSTORE FIELD AND PATH NAME STRINGS, HELPERS
 ******************************************************************************
 */
#define XENSND_DRIVER_NAME		"vsnd"

#define XENSND_LIST_SEPARATOR		","
/* Field names */
#define XENSND_FIELD_BE_VERSIONS	"versions"
#define XENSND_FIELD_FE_VERSION		"version"
#define XENSND_FIELD_VCARD_SHORT_NAME	"short-name"
#define XENSND_FIELD_VCARD_LONG_NAME	"long-name"
#define XENSND_FIELD_RING_REF		"ring-ref"
#define XENSND_FIELD_EVT_CHNL		"event-channel"
#define XENSND_FIELD_EVT_RING_REF	"evt-ring-ref"
#define XENSND_FIELD_EVT_EVT_CHNL	"evt-event-channel"
#define XENSND_FIELD_DEVICE_NAME	"name"
#define XENSND_FIELD_TYPE		"type"
#define XENSND_FIELD_STREAM_UNIQUE_ID	"unique-id"
#define XENSND_FIELD_CHANNELS_MIN	"channels-min"
#define XENSND_FIELD_CHANNELS_MAX	"channels-max"
#define XENSND_FIELD_SAMPLE_RATES	"sample-rates"
#define XENSND_FIELD_SAMPLE_FORMATS	"sample-formats"
#define XENSND_FIELD_BUFFER_SIZE	"buffer-size"

/* Stream type field values. */
#define XENSND_STREAM_TYPE_PLAYBACK	"p"
#define XENSND_STREAM_TYPE_CAPTURE	"c"
/* Sample rate max string length */
#define XENSND_SAMPLE_RATE_MAX_LEN	11
/* Sample format field values */
#define XENSND_SAMPLE_FORMAT_MAX_LEN	24

#define XENSND_PCM_FORMAT_S8_STR	"s8"
#define XENSND_PCM_FORMAT_U8_STR	"u8"
#define XENSND_PCM_FORMAT_S16_LE_STR	"s16_le"
#define XENSND_PCM_FORMAT_S16_BE_STR	"s16_be"
#define XENSND_PCM_FORMAT_U16_LE_STR	"u16_le"
#define XENSND_PCM_FORMAT_U16_BE_STR	"u16_be"
#define XENSND_PCM_FORMAT_S24_LE_STR	"s24_le"
#define XENSND_PCM_FORMAT_S24_BE_STR	"s24_be"
#define XENSND_PCM_FORMAT_U24_LE_STR	"u24_le"
#define XENSND_PCM_FORMAT_U24_BE_STR	"u24_be"
#define XENSND_PCM_FORMAT_S32_LE_STR	"s32_le"
#define XENSND_PCM_FORMAT_S32_BE_STR	"s32_be"
#define XENSND_PCM_FORMAT_U32_LE_STR	"u32_le"
#define XENSND_PCM_FORMAT_U32_BE_STR	"u32_be"
#define XENSND_PCM_FORMAT_F32_LE_STR	"float_le"
#define XENSND_PCM_FORMAT_F32_BE_STR	"float_be"
#define XENSND_PCM_FORMAT_F64_LE_STR	"float64_le"
#define XENSND_PCM_FORMAT_F64_BE_STR	"float64_be"
#define XENSND_PCM_FORMAT_IEC958_SUBFRAME_LE_STR "iec958_subframe_le"
#define XENSND_PCM_FORMAT_IEC958_SUBFRAME_BE_STR "iec958_subframe_be"
#define XENSND_PCM_FORMAT_MU_LAW_STR	"mu_law"
#define XENSND_PCM_FORMAT_A_LAW_STR	"a_law"
#define XENSND_PCM_FORMAT_IMA_ADPCM_STR	"ima_adpcm"
#define XENSND_PCM_FORMAT_MPEG_STR	"mpeg"
#define XENSND_PCM_FORMAT_GSM_STR	"gsm"

/*
 ******************************************************************************
 *                          STATUS RETURN CODES
 ******************************************************************************
 *
 * Status return code is zero on success and -XEN_EXX on failure.
 *
 ******************************************************************************
 *                              Assumptions
 ******************************************************************************
 * o usage of grant reference 0 as invalid grant reference:
 *   grant reference 0 is valid, but never exposed to a PV driver,
 *   because of the fact it is already in use/reserved by the PV console.
 * o all references in this document to page sizes must be treated
 *   as pages of size XEN_PAGE_SIZE unless otherwise noted.
 *
 ******************************************************************************
 *       Description of the protocol between frontend and backend driver
 ******************************************************************************
 *
 * The two halves of a Para-virtual sound driver communicate with
 * each other using shared pages and event channels.
 * Shared page contains a ring with request/response packets.
 *
 * Packets, used for input/output operations, e.g. read/write, set/get volume,
 * etc., provide offset/length fields in order to allow asynchronous protocol
 * operation with buffer space sharing: part of the buffer allocated at
 * XENSND_OP_OPEN can be used for audio samples and part, for example,
 * for volume control.
 *
 * All reserved fields in the structures below must be 0.
 *
 *---------------------------------- Requests ---------------------------------
 *
 * All request packets have the same length (64 octets)
 * All request packets have common header:
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                |    operation   |    reserved    | 4
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 8
 * +----------------+----------------+----------------+----------------+
 *   id - uint16_t, private guest value, echoed in response
 *   operation - uint8_t, operation code, XENSND_OP_???
 *
 * For all packets which use offset and length:
 *   offset - uint32_t, read or write data offset within the shared buffer,
 *     passed with XENSND_OP_OPEN request, octets,
 *     [0; XENSND_OP_OPEN.buffer_sz - 1].
 *   length - uint32_t, read or write data length, octets
 *
 * Request open - open a PCM stream for playback or capture:
 *
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                | XENSND_OP_OPEN |    reserved    | 4
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 8
 * +----------------+----------------+----------------+----------------+
 * |                             pcm_rate                              | 12
 * +----------------+----------------+----------------+----------------+
 * |  pcm_format    |  pcm_channels  |             reserved            | 16
 * +----------------+----------------+----------------+----------------+
 * |                             buffer_sz                             | 20
 * +----------------+----------------+----------------+----------------+
 * |                           gref_directory                          | 24
 * +----------------+----------------+----------------+----------------+
 * |                             period_sz                             | 28
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 32
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 64
 * +----------------+----------------+----------------+----------------+
 *
 * pcm_rate - uint32_t, stream data rate, Hz
 * pcm_format - uint8_t, XENSND_PCM_FORMAT_XXX value
 * pcm_channels - uint8_t, number of channels of this stream,
 *   [channels-min; channels-max]
 * buffer_sz - uint32_t, buffer size to be allocated, octets
 * period_sz - uint32_t, event period size, octets
 *   This is the requested value of the period at which frontend would
 *   like to receive XENSND_EVT_CUR_POS notifications from the backend when
 *   stream position advances during playback/capture.
 *   It shows how many octets are expected to be played/captured before
 *   sending such an event.
 *   If set to 0 no XENSND_EVT_CUR_POS events are sent by the backend.
 *
 * gref_directory - grant_ref_t, a reference to the first shared page
 *   describing shared buffer references. At least one page exists. If shared
 *   buffer size  (buffer_sz) exceeds what can be addressed by this single page,
 *   then reference to the next page must be supplied (see gref_dir_next_page
 *   below)
 */

struct xensnd_open_req {
	uint32_t pcm_rate;
	uint8_t pcm_format;
	uint8_t pcm_channels;
	uint16_t reserved;
	uint32_t buffer_sz;
	grant_ref_t gref_directory;
	uint32_t period_sz;
};

/*
 * Shared page for XENSND_OP_OPEN buffer descriptor (gref_directory in the
 *   request) employs a list of pages, describing all pages of the shared data
 *   buffer:
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |                        gref_dir_next_page                         | 4
 * +----------------+----------------+----------------+----------------+
 * |                              gref[0]                              | 8
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                              gref[i]                              | i*4+8
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             gref[N - 1]                           | N*4+8
 * +----------------+----------------+----------------+----------------+
 *
 * gref_dir_next_page - grant_ref_t, reference to the next page describing
 *   page directory. Must be 0 if there are no more pages in the list.
 * gref[i] - grant_ref_t, reference to a shared page of the buffer
 *   allocated at XENSND_OP_OPEN
 *
 * Number of grant_ref_t entries in the whole page directory is not
 * passed, but instead can be calculated as:
 *   num_grefs_total = (XENSND_OP_OPEN.buffer_sz + XEN_PAGE_SIZE - 1) /
 *       XEN_PAGE_SIZE
 */

struct xensnd_page_directory {
	grant_ref_t gref_dir_next_page;
	grant_ref_t gref[1]; /* Variable length */
};

/*
 *  Request close - close an opened pcm stream:
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                | XENSND_OP_CLOSE|    reserved    | 4
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 8
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 64
 * +----------------+----------------+----------------+----------------+
 *
 * Request read/write - used for read (for capture) or write (for playback):
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                |   operation    |    reserved    | 4
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 8
 * +----------------+----------------+----------------+----------------+
 * |                              offset                               | 12
 * +----------------+----------------+----------------+----------------+
 * |                              length                               | 16
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 20
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 64
 * +----------------+----------------+----------------+----------------+
 *
 * operation - XENSND_OP_READ for read or XENSND_OP_WRITE for write
 */

struct xensnd_rw_req {
	uint32_t offset;
	uint32_t length;
};

/*
 * Request set/get volume - set/get channels' volume of the stream given:
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                |   operation    |    reserved    | 4
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 8
 * +----------------+----------------+----------------+----------------+
 * |                              offset                               | 12
 * +----------------+----------------+----------------+----------------+
 * |                              length                               | 16
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 20
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 64
 * +----------------+----------------+----------------+----------------+
 *
 * operation - XENSND_OP_SET_VOLUME for volume set
 *   or XENSND_OP_GET_VOLUME for volume get
 * Buffer passed with XENSND_OP_OPEN is used to exchange volume
 * values:
 *
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |                             channel[0]                            | 4
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             channel[i]                            | i*4
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                           channel[N - 1]                          | (N-1)*4
 * +----------------+----------------+----------------+----------------+
 *
 * N = XENSND_OP_OPEN.pcm_channels
 * i - uint8_t, index of a channel
 * channel[i] - sint32_t, volume of i-th channel
 * Volume is expressed as a signed value in steps of 0.001 dB,
 * while 0 being 0 dB.
 *
 * Request mute/unmute - mute/unmute stream:
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                |   operation    |    reserved    | 4
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 8
 * +----------------+----------------+----------------+----------------+
 * |                              offset                               | 12
 * +----------------+----------------+----------------+----------------+
 * |                              length                               | 16
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 20
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 64
 * +----------------+----------------+----------------+----------------+
 *
 * operation - XENSND_OP_MUTE for mute or XENSND_OP_UNMUTE for unmute
 * Buffer passed with XENSND_OP_OPEN is used to exchange mute/unmute
 * values:
 *
 *                                   0                                 octet
 * +----------------+----------------+----------------+----------------+
 * |                             channel[0]                            | 4
 * +----------------+----------------+----------------+----------------+
 * +/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             channel[i]                            | i*4
 * +----------------+----------------+----------------+----------------+
 * +/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                           channel[N - 1]                          | (N-1)*4
 * +----------------+----------------+----------------+----------------+
 *
 * N = XENSND_OP_OPEN.pcm_channels
 * i - uint8_t, index of a channel
 * channel[i] - uint8_t, non-zero if i-th channel needs to be muted/unmuted
 *
 *------------------------------------ N.B. -----------------------------------
 *
 * The 'struct xensnd_rw_req' is also used for XENSND_OP_SET_VOLUME,
 * XENSND_OP_GET_VOLUME, XENSND_OP_MUTE, XENSND_OP_UNMUTE.
 *
 * Request stream running state change - trigger PCM stream running state
 * to start, stop, pause or resume:
 *
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                |   _OP_TRIGGER  |    reserved    | 4
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 8
 * +----------------+----------------+----------------+----------------+
 * |      type      |                     reserved                     | 12
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 16
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 64
 * +----------------+----------------+----------------+----------------+
 *
 * type - uint8_t, XENSND_OP_TRIGGER_XXX value
 */

struct xensnd_trigger_req {
	uint8_t type;
};

/*
 * Request stream parameter ranges: request intervals and
 *   masks of supported ranges for stream configuration values.
 *
 *   Sound device configuration for a particular stream is a limited subset
 *   of the multidimensional configuration available on XenStore, e.g.
 *   once the frame rate has been selected there is a limited supported range
 *   for sample rates becomes available (which might be the same set configured
 *   on XenStore or less). For example, selecting 96kHz sample rate may limit
 *   number of channels available for such configuration from 4 to 2, etc.
 *   Thus, each call to XENSND_OP_HW_PARAM_QUERY may reduce configuration
 *   space making it possible to iteratively get the final stream configuration,
 *   used in XENSND_OP_OPEN request.
 *
 *   See response format for this request.
 *
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                | _HW_PARAM_QUERY|    reserved    | 4
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 8
 * +----------------+----------------+----------------+----------------+
 * |                     formats mask low 32-bit                       | 12
 * +----------------+----------------+----------------+----------------+
 * |                     formats mask high 32-bit                      | 16
 * +----------------+----------------+----------------+----------------+
 * |                              min rate                             | 20
 * +----------------+----------------+----------------+----------------+
 * |                              max rate                             | 24
 * +----------------+----------------+----------------+----------------+
 * |                            min channels                           | 28
 * +----------------+----------------+----------------+----------------+
 * |                            max channels                           | 32
 * +----------------+----------------+----------------+----------------+
 * |                         min buffer frames                         | 36
 * +----------------+----------------+----------------+----------------+
 * |                         max buffer frames                         | 40
 * +----------------+----------------+----------------+----------------+
 * |                         min period frames                         | 44
 * +----------------+----------------+----------------+----------------+
 * |                         max period frames                         | 48
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 52
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 64
 * +----------------+----------------+----------------+----------------+
 *
 * formats - uint64_t, bit mask representing values of the parameter
 *     made as bitwise OR of (1 << XENSND_PCM_FORMAT_XXX) values
 *
 * For interval parameters:
 *   min - uint32_t, minimum value of the parameter
 *   max - uint32_t, maximum value of the parameter
 *
 * Frame is defined as a product of the number of channels by the
 * number of octets per one sample.
 */

struct xensnd_query_hw_param {
	uint64_t formats;
	struct {
		uint32_t min;
		uint32_t max;
	} rates;
	struct {
		uint32_t min;
		uint32_t max;
	} channels;
	struct {
		uint32_t min;
		uint32_t max;
	} buffer;
	struct {
		uint32_t min;
		uint32_t max;
	} period;
};

/*
 *---------------------------------- Responses --------------------------------
 *
 * All response packets have the same length (64 octets)
 *
 * All response packets have common header:
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                |    operation   |    reserved    | 4
 * +----------------+----------------+----------------+----------------+
 * |                              status                               | 8
 * +----------------+----------------+----------------+----------------+
 *
 * id - uint16_t, copied from the request
 * operation - uint8_t, XENSND_OP_* - copied from request
 * status - int32_t, response status, zero on success and -XEN_EXX on failure
 *
 *
 * HW parameter query response - response for XENSND_OP_HW_PARAM_QUERY:
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                |    operation   |    reserved    | 4
 * +----------------+----------------+----------------+----------------+
 * |                              status                               | 8
 * +----------------+----------------+----------------+----------------+
 * |                     formats mask low 32-bit                       | 12
 * +----------------+----------------+----------------+----------------+
 * |                     formats mask high 32-bit                      | 16
 * +----------------+----------------+----------------+----------------+
 * |                              min rate                             | 20
 * +----------------+----------------+----------------+----------------+
 * |                              max rate                             | 24
 * +----------------+----------------+----------------+----------------+
 * |                            min channels                           | 28
 * +----------------+----------------+----------------+----------------+
 * |                            max channels                           | 32
 * +----------------+----------------+----------------+----------------+
 * |                         min buffer frames                         | 36
 * +----------------+----------------+----------------+----------------+
 * |                         max buffer frames                         | 40
 * +----------------+----------------+----------------+----------------+
 * |                         min period frames                         | 44
 * +----------------+----------------+----------------+----------------+
 * |                         max period frames                         | 48
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 52
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 64
 * +----------------+----------------+----------------+----------------+
 *
 * Meaning of the values in this response is the same as for
 * XENSND_OP_HW_PARAM_QUERY request.
 */

/*
 *----------------------------------- Events ----------------------------------
 *
 * Events are sent via shared page allocated by the front and propagated by
 *   evt-event-channel/evt-ring-ref XenStore entries
 * All event packets have the same length (64 octets)
 * All event packets have common header:
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                |      type      |   reserved     | 4
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 8
 * +----------------+----------------+----------------+----------------+
 *
 * id - uint16_t, event id, may be used by front
 * type - uint8_t, type of the event
 *
 *
 * Current stream position - event from back to front when stream's
 *   playback/capture position has advanced:
 *         0                1                 2               3        octet
 * +----------------+----------------+----------------+----------------+
 * |               id                |   _EVT_CUR_POS |   reserved     | 4
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 8
 * +----------------+----------------+----------------+----------------+
 * |                         position low 32-bit                       | 12
 * +----------------+----------------+----------------+----------------+
 * |                         position high 32-bit                      | 16
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 20
 * +----------------+----------------+----------------+----------------+
 * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
 * +----------------+----------------+----------------+----------------+
 * |                             reserved                              | 64
 * +----------------+----------------+----------------+----------------+
 *
 * position - current value of stream's playback/capture position, octets
 *
 */

struct xensnd_cur_pos_evt {
	uint64_t position;
};

struct xensnd_req {
	uint16_t id;
	uint8_t operation;
	uint8_t reserved[5];
	union {
		struct xensnd_open_req open;
		struct xensnd_rw_req rw;
		struct xensnd_trigger_req trigger;
		struct xensnd_query_hw_param hw_param;
		uint8_t reserved[56];
	} op;
};

struct xensnd_resp {
	uint16_t id;
	uint8_t operation;
	uint8_t reserved;
	int32_t status;
	union {
		struct xensnd_query_hw_param hw_param;
		uint8_t reserved1[56];
	} resp;
};

struct xensnd_evt {
	uint16_t id;
	uint8_t type;
	uint8_t reserved[5];
	union {
		struct xensnd_cur_pos_evt cur_pos;
		uint8_t reserved[56];
	} op;
};

DEFINE_RING_TYPES(xen_sndif, struct xensnd_req, struct xensnd_resp);

/*
 ******************************************************************************
 *                        Back to front events delivery
 ******************************************************************************
 * In order to deliver asynchronous events from back to front a shared page is
 * allocated by front and its granted reference propagated to back via
 * XenStore entries (evt-ring-ref/evt-event-channel).
 * This page has a common header used by both front and back to synchronize
 * access and control event's ring buffer, while back being a producer of the
 * events and front being a consumer. The rest of the page after the header
 * is used for event packets.
 *
 * Upon reception of an event(s) front may confirm its reception
 * for either each event, group of events or none.
 */

struct xensnd_event_page {
	uint32_t in_cons;
	uint32_t in_prod;
	uint8_t reserved[56];
};

#define XENSND_EVENT_PAGE_SIZE XEN_PAGE_SIZE
#define XENSND_IN_RING_OFFS (sizeof(struct xensnd_event_page))
#define XENSND_IN_RING_SIZE (XENSND_EVENT_PAGE_SIZE - XENSND_IN_RING_OFFS)
#define XENSND_IN_RING_LEN (XENSND_IN_RING_SIZE / sizeof(struct xensnd_evt))
#define XENSND_IN_RING(page) \
	((struct xensnd_evt *)((char *)(page) + XENSND_IN_RING_OFFS))
#define XENSND_IN_RING_REF(page, idx) \
	(XENSND_IN_RING((page))[(idx) % XENSND_IN_RING_LEN])

#endif /* __XEN_PUBLIC_IO_SNDIF_H__ */

cmd: